How To Fix SOS_MAPPING851 - The TYPE field can only exist in the root class

SAP Error Message - Details

• Message type: E = Error

• Message class: SOS_MAPPING - Object Services: Persistence Mapping for Messages

• Message number: 851

• Message text: The TYPE field can only exist in the root class

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message SOS_MAPPING851 - The TYPE field can only exist in the root class ?

  The SAP error message SOS_MAPPING851 indicates that there is an issue with the mapping of a data structure, specifically related to the TYPE field in a class hierarchy. This error typically arises in the context of Object-Oriented Programming (OOP) in ABAP, particularly when dealing with class definitions and inheritance.
  Cause:
  The error occurs when the TYPE field is defined in a subclass rather than in the root class of the inheritance hierarchy. In ABAP OOP, certain fields, like TYPE, are expected to be defined only in the root class. If you attempt to define or use the TYPE field in a subclass, the system raises this error.
  Solution:
  To resolve the SOS_MAPPING851 error, you should:
  
  
  Check Class Definitions: Review the class definitions in your inheritance hierarchy. Ensure that the TYPE field is defined only in the root class and not in any subclasses.
  
  
  Modify Subclass Definitions: If you find that the TYPE field is incorrectly defined in a subclass, remove it from the subclass definition. Instead, ensure that the subclass inherits the TYPE field from the root class.
  
  
  Recompile Classes: After making the necessary changes, recompile the classes to ensure that the changes take effect.
  
  
  Test the Changes: Execute the relevant program or transaction to verify that the error has been resolved.
  
  
  Related Information:
  
  ABAP OOP Concepts: Familiarize yourself with the principles of Object-Oriented Programming in ABAP, including class definitions, inheritance, and the use of attributes.
  SAP Documentation: Refer to the official SAP documentation for more details on class definitions and the rules governing the use of fields in class hierarchies.
  Debugging Tools: Utilize SAP debugging tools to trace the execution and identify where the TYPE field is being incorrectly referenced.
  
  By following these steps, you should be able to resolve the SOS_MAPPING851 error and ensure that your class definitions adhere to the required structure in ABAP OOP.